I tried The Supreme Roastworks "Earth" blend at home, with reasonable success. It took two shots to dial in and the taste of the third was quite good. Not quite at the level of the one I got from them, but really satifsying.

The bottomless portafilter revealed a pour that was a little more "lively" and unstable than with the cheaper robusta-blended coffee, but there were no sprites or serious channeling issues. A little more work on technique might make it perfect and improve the taste further.

So it seems the coffee was to blame, at least to a significant degree. Interesting how some coffees are easy to use while others are almost impossible. This new one is in the middle somewhere.

Perhaps I'll try to blend in a little of the robusta blended coffee into the hopeless one just to see what happens.

I'm not exactly sure how much coffee that has gone through the blender yet, perhaps a little over two kilos. Perhaps things will indeed get a little easier with time as it breaks in.